Add qbswap for a memory region

The compiler was generating some vectorized code for qresource.cpp but
it wasn't very efficient. So improve upon it and make use in other
places where we read UTF-16BE strings.

[ChangeLog][QtCore] Added an overload of q{To,From}{Big,Little}Endian
that operates on a memory region.

Change-Id: I6a540578e810472bb455fffd1531fa2f1d724dfc
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/corelib/global/qendian.h b/src/corelib/global/qendian.h
index a14fce23f8..135bc4460b 100644
--- a/src/corelib/global/qendian.h
+++ b/src/corelib/global/qendian.h
@@ -157,6 +157,14 @@ template <typename T> inline void qbswap(const T src, void *dest)
     qToUnaligned<T>(qbswap<T>(src), dest);
 }
 
+template <int Size> void *qbswap(const void *source, qsizetype count, void *dest) noexcept;
+template<> inline void *qbswap<1>(const void *source, qsizetype count, void *dest) noexcept
+{
+    return source != dest ? memcpy(dest, source, size_t(count)) : dest;
+}
+template<> Q_CORE_EXPORT void *qbswap<2>(const void *source, qsizetype count, void *dest) noexcept;
+template<> Q_CORE_EXPORT void *qbswap<4>(const void *source, qsizetype count, void *dest) noexcept;
+template<> Q_CORE_EXPORT void *qbswap<8>(const void *source, qsizetype count, void *dest) noexcept;
 
 #if Q_BYTE_ORDER == Q_BIG_ENDIAN
 
@@ -172,6 +180,15 @@ template <typename T> inline void qToBigEndian(T src, void *dest)
 { qToUnaligned<T>(src, dest); }
 template <typename T> inline void qToLittleEndian(T src, void *dest)
 { qbswap<T>(src, dest); }
+
+template <typename T> inline void qToBigEndian(const void *source, qsizetype count, void *dest)
+{ if (source != dest) memcpy(dest, source, count * sizeof(T)); }
+template <typename T> inline void qToLittleEndian(const void *source, qsizetype count, void *dest)
+{ qbswap<sizeof(T)>(source, count, dest); }
+template <typename T> inline void qFromBigEndian(const void *source, qsizetype count, void *dest)
+{ if (source != dest) memcpy(dest, source, count * sizeof(T)); }
+template <typename T> inline void qFromLittleEndian(const void *source, qsizetype count, void *dest)
+{ qbswap<sizeof(T)>(source, count, dest); }
 #else // Q_LITTLE_ENDIAN
 
 template <typename T> inline Q_DECL_CONSTEXPR T qToBigEndian(T source)
@@ -187,6 +204,14 @@ template <typename T> inline void qToBigEndian(T src, void *dest)
 template <typename T> inline void qToLittleEndian(T src, void *dest)
 { qToUnaligned<T>(src, dest); }
 
+template <typename T> inline void qToBigEndian(const void *source, qsizetype count, void *dest)
+{ qbswap<sizeof(T)>(source, count, dest); }
+template <typename T> inline void qToLittleEndian(const void *source, qsizetype count, void *dest)
+{ if (source != dest) memcpy(dest, source, count * sizeof(T)); }
+template <typename T> inline void qFromBigEndian(const void *source, qsizetype count, void *dest)
+{ qbswap<sizeof(T)>(source, count, dest); }
+template <typename T> inline void qFromLittleEndian(const void *source, qsizetype count, void *dest)
+{ if (source != dest) memcpy(dest, source, count * sizeof(T)); }
 #endif // Q_BYTE_ORDER == Q_BIG_ENDIAN